This invention relates to a circuit arrangement for testing the operation of a current monitoring circuit for a power transistor, which consists of several single transistors connected in parallel, through which a fraction of the total current supplied to the power transistor flows, where a monitoring signal proportional to the current flowing through one of the single transistors, is supplied to the current monitoring circuit, which generates an alarm signal when this signal exceeds a specified threshold value.
Texas Instruments Incorporated have already produced and marketed an integrated circuit of the above type under the type designation TRICO1O6, in which a power transistor is present, which controls a current flowing through a motor. In order to monitor the current flowing through the motor, a current monitoring circuit is used, which contains a comparator, which always emits a monitoring signal when the current flowing through the power transistor and thus also through the motor, exceeds a predetermined value. It was only possible to monitor this integrated circuit, in particular the current monitoring function, in this circuit after completion and in practical operation with the high currents actually flowing through the motor. However, when producing integrated semi-conductor circuits, it is desirable to check the operation of at least parts of the circuit, at the earliest possible stage of production, preferably even before bonding and contacting. For these checking processes, test probes are used which are/applied to the bond contact surfaces, which are to be contacted at a later stage, of the integrated semiconductor circuit and through which the currents and control signals are supplied during test running. Checking the current monitoring circuit of the power transistor in the case of the known circuit described, is, however, not possible with test probes, because with test probes, currents of more than 1 A cannot be supplied because of the small contact surfaces.